Coupled micromorphological and stable isotope analysis of Quaternary calcrete development

Abstract

12 13Pedogenic calcretes are widespread in arid and semi-arid regions. Using calcrete profiles from four 14 river terraces of the Rio Alias in southeast Spain, this study explores the potential of using detailed 15 micromorphological and stable isotopic analysis to more fully understand the impacts of Quaternary 16 environmental change on calcrete development. The four profiles increase in carbonate complexity 17 with progressive age, reflecting calcretisation over multiple glacial-interglacial cycles since MIS 9 (c. to the same environmental parameter, which is inferred to be relative aridity. The study reveals that 23 the detailed co-analysis of calcrete micromorphology and stable isotope signatures can allow patterns 24 of calcrete formation to be placed into a wider palaeoclimatic context. This demonstrates the potential 25 of this technique to more reliably constrain the palaeoenvironmental significance of secondary 26 carbonates in dryland settings where other proxy records may be poorly preserved. 27 28

Relationships between fluvial evolution and karstification related to climatic, tectonic and eustatic forcing in temperate regions

“…The U-series ages were used to identify several abrupt warming phases during MIS 3 -a cold period recorded in the Greenland ice cores and in the Grande Pile peat record from the Southern Vosges mountains, NE France (Pons-Branchu et al, 2010). Useries analysis of pedogenic and groundwater calcrete horizons has also been used to constrain the timing of fluvial aggradation in karst settings such as the Sorbas basin of SE Spain (Candy et al, 2015) and the limestone Orjen massif, western Montenegro (Adamson et al, 2014), respectively.…”

“…Secondary carbonate-based chronologies can be used alongside stable oxygen (δ 18 O) and carbon (δ 13 C) isotope ratio analysis to provide a record of interglacial climatic changes (Dabkowski et al, 2011(Dabkowski et al, , 2016, such as interglacial tufas in France (e.g. La-Celle-sur-Seine, Paris Region: MIS 11 and Caours, Somme Basin: MIS 5e) and pedogenic calcretes in Southeast Spain (Adamson et al, 2015;Gázquez et al, 2016).…”

Of ice and water: Quaternary fluvial response to glacial forcing

“…Candy et al 2005Candy et al , 2012Woodward et al, 2008;Adamson et al, 2014). This means that a Pleistocene sedimentary sequence may contain multiple calcite horizons formed during different climate phases (Adamson et al, 2015).As discussed above, accurate interpretation of U-series ages therefore relies on a detailed understanding of the morphosedimentary and topographic context, as well as a detailed and systematic dating programme (Candy et al, 2004).…”

Pedogenic carbonates: Forms and formation processes

“…Topography and soil position in the landscape and soil age). The thickness of calcrete, its location, micromorphology and formation stages are useful indicators of development and age of soils and landscapes(Adamson et al, 2015;Gile et al, 1966).Insert Fig. 7 about here Insert Fig.…”